Expansible chamber.



H. E. OXNARD.

EXPANSIBLE CHAMBER.

V u V v APPLIUATO'N FILED MAY18,1910. 15,038,635, A Patented Sept. 17,1912.

4 SHEETS-SHEET 1.

www I imam, camf( #4f/...j

H. E. OXNARD.

I EXPANSIBLE CHAMBER.

APPLICATION FILED MAY 11;, 1910.

pa atented Sept. 17', 1912.

SHEETS-SHEET 2.

HQ .Hfoxmm` EXPANSIBLB CHAMBER.

APPLICATION TILE?) MAY 18, 1910 1,038,636. Patented sept. 17,1912.

4 SHEETS-SHEET 34 MEJS% /NVE/VTUH HEM? Y E. x/VA R0 5 Y Hfs A Tra/JNE Ys VV/T/vfssfs y H. E. OXNARD.n

EXPANSIBLE CHAMBER.

. APPLICATION FILED MAY 18, 1910.

1,053,653@ Pantd Sept. 1'?, 19m.

4 SHEBTSr-SHEET 4 '1'5 sent'edas aspring for absorbing shocks and ldd@ @TA il fr enten.

HlEll'l'EtIi E. OXNARD, 0F NEWTON, MASSACHUSETTS.

nitransienn CHAMBER.

Speeication of Letters Patent. i Patented Spt, QEQL.

Application filed May 1S, 1910. Serial No. 562,011. y

To "all iti/rom z'' may concern.'

Be .itknoivn that. I, HENRY E. OXNARD, a citizen of the United States, residing at Newtonin the county of Middlesex and State of Massachusetts, have invented new and useful. Improvements in- Expansible Chambers, of which the following is a specification. A

This inventionv relates to expansible chambers. Y.

v tain air onother expansible lduid for sustainlili ing stresses 'elast-ically, or to act as a. hulfcr `for receiving any force; andit is here reprejolts oft a vehicle; altholtgh the apparatus heredescribed and suitable modifications of it may loe -used in many other connections without departing from the scope ot' the present patent.

It is among the purposes of the invention to provide a chamber in which fluit-l may be contained at high pressures, having a plunger reciprocating inward and outward -without leakage and zllnost'witliout friction.

As applied to a pneuinatiespring the in'- v vention seelrs to provide Wide limits for the range of travel between the expanded and ',tlue'compressed positions oli' the spring; an

easy and 'freely responsive action olthe spring, with a minimum of Wear, resulting from the elimination of friction; and great itrength, resulting from the capability of containing air at exceedingly high pressures without leakage or rupture.

The invention also comprises .improve ments ina number ci details of construction ot vsuch apparatus, and in the method of arranging the saine in connection with the parte to which it is attached.

lt comprises improvements in tliey strucH .ture, arrangement and the fastening ot' the septun'igalso improvements in the form of the air space, dividing tl'ie same into tivo parts; and in the connections between the parts, eliminating tlie violence of reaction heretofore common in springs; and in the combination thereof with the vehicle traine or body galso improvements in the methods or guiding; the travel` ot" the movable por tions ol? the chamber; and improvements in other respects which appear in the follow .inn detailed description..

lo the drawings: Figure l an elevation,y

sectioned through the center, of apparatus embodying the invention; t1"1g..2 1s a' plan; View of the saine, sectioned on, thelin'e. .y of Fig. l; Fig. 3 is a sectional eleve-tieniofl a dii'erent emloodimcnt.oitl the .inventionqno Fig. 4: is.' sectional elevation-ot still ani other embodiment of the invention lligff u is a sectional View of a detail; Fig. I6 shows a slightly diilerent form of septum .tastening;"and Fig. 7 shows application ofthe invention to a vehicle; l l Reierring"to the' drawings: An enpansible chamber having correlativel moving opf-f posit@ walls is here shown in the forni of j round casing here represented as a' cylinder" 10, containing a plunger 1l. which slides'in." packing 12 and (in the form repreeeiited in Fig. 1) is guided and sustained Witlrits axis coincident with the axis of the cylinfj der by hinged braces 13, [which are' pivoted L' at 14 tothe casing,` at l5 to tlie plunger and at 16 to each other. One inemheroli. the chamber, here the plunger, rests loosely in a bearing',V which maj;r be rigid on axle of a Vehicle; and theotlier ineini'iei i here the cylinden supports the `lvehicle The function of the packing, 12 s to luliricate and assist in guiding tile lpluieger. For retaining .air Within the "chaniber, reliance is placed upon a septum 9.0 which is fastened to the pluri er and to the cylinder. rllhis septum is of niglily llexioley material',"impervious to air, and arranged in the torni ot' an evcrted sleeve @Wing tothe peculiar construction of the septuifn5 the surface thereof 'which fits against the exterior of the plunger il is also capable of fitting against the interior of the cylin der l0, 'notwithstanding' the larger-diameter and area of the latter. l 'llie diameter of tile plunger is made slightly. less than that or" tlie'cylinder, in which it tra vels differing: by an amount butlitt-l'e greater than the doubie thickness of tlie septum. The thickness of' the septum and the diversity of diameter of the cylinder and plunger are exaggerated in the drawings. for the salie oi.l clearuess, over tlie dimensions which are 'found best in practice and which are preferred.- The eenA tuin mav he composed ct' two layers ofY l'iighly liexilole leather 3l. and 33, Witlnalayer o'l rubber 32'inte1'ifenli31g-tlie whole being fastened together adhesiveljr they Work one integral `piece, The r1 ,ser end of the septum, may he-estencdin ,the manner shown in the dravvinn'shin 'which an annularcup 2 is formedfin the plunger lll@ head, .iilled 'with a rather thick bedo rubJ bei; A ring or disk 24 presses down upon this, and the outer leather 3b ofthe septum is embraced between them, being here scpz'rated from its rubber 32 andc A'impr-3d inivard toward the anis or cut into iaps'ivhich are bent inward. The rubber is iittted outside the rubber disk 24, to the cylindrical periphery of which it adheres bv rubber cement the other leather 3l is next outside; and the Whole is preferably protected by a lightinclosing ring or fillet surroiunling the plunger head; and a brass cap which may be Screwed upon the plun :r head, holds all the parts in place. Walls of the cup Q2 are serrated with a considerable number of ring shaped depressions 19 clearly represented in cross section in the drawings. The rubber bed 23 lits Wit-h sui'lieienttightness radially, and is pressed inward with sufficient force axially, so that it bulges into these serrations, as represented in another fastening shown enlarged in Fig, By this means a joint iur pcrvious to air is obtained on all the interior surfaces of the cup, bot-h by the bed Q3 'and by the ring or disk 24, The space betweeny these rings which is not occupied radially by leather may be llled with a thin ring filling ofrubber :27 it desired, in order to maintain a rectaim'ular bearing of rubber ring 522i upon the es ot' cup lt will be ol'iserved that vvhet-her this ringr fillinge employed or not, theapproach ot air to the end of leather layer is occluded by mut-u ally contacting surfaces of rubber. The other end of the septunrniay be arranged at the opposite end ot the cylinder, as indicated in Fie". l. The fastening is similar to that just described. The plunger has an axial recess 28 into which tits a stili rod 29 projecting from the other end wall 30 of the cylinder; and this rod Iiireferably tits rather loosely,- so that tli'ere will be soineleakage past it, the looseness being exaggerated in v the drawings,

'and capacity.

The clian'iber as here represented of univiiorin 'diameter throughout its length, but has an extension 35, which is reached through passage 3l, which niay be ol. any desired diameter and of any desiredshapc This extension is a closed receiver between which and the chamber air llo automatically, in either direction, during thc normal operation of the apparatus. It is one feature ot' the invention that this extension may constitute part of the trauie of the vehicle, which may be hollenv or tubular; and. it one spring' he placed at each Wheel, the same rmtcivcr, comprised in the various n'uznbcrs el the tubular trameVA may connuimicate willigy ch ot thc springchanr bers .in Fig. l l' is is ri presented convoi ticnall" by indi in# a tubular piece su b moral n.; the cylinder, whichrmay yeste".

as far as desired in either direction, or be connected 'with any other tube, its ends being represented closed. The effect of this receiver or extension of the expansible chainber is to increase the distance of elastic yield et' the spring when -its load is increased, or a shock is encountered, over the extent The capacity and dimensions of thc extension'n'iay be computed in any given case by consideration of the normal increase of'load which it is assumed will be encountered, and the capacity of the chamber 10 under normal conditions, the computation being made in the product of the volume by the pressure ol a confined body of airis a constant quantity. Accordingly, if it is desired that a small torce or addition of Weight shall produce a relatively large yielding of the sprin(r the extension of the chamber should be relatively large, because thereby the proportionate change of volume, corresponding to th'atincrease of pressure upon the contents, would amount to more inches of travelot pacity otv the receiver were so small to add relatively little to the capacity of the chamber. It Will be understood that the torefroing assumes'the existence ot a copious ness of communication between the chamber and extension so that when an impact is re ceived they acty substantially as a unit, the rapidity of contraction of the chamber under Working conditions being substantially unretarded by smallness of thev passage thence into the extension. The vertical space available for a spring under a vehicle, or, for example, Within the hub of the Wheel of a vehicle is frequently so limited that heretofore the easy, resilient effect ol a plun gerhaving a long travel could not be had, because the rapid proportionate compression per inch of travel quickly stops the plunger. The device above described, of providing an external receiver constituting anextension of the chamber, which may be placed else- Where, Wherever there is room ,and need not be vertical, enlarges the uses of this type o'r`. spring, and improves the action, because by this device practically the Whole ot' the Within the plungers travel.

The invention further comprises means whereby the spring under ordinary conditions will atlord the vehicle an easy resiliency, the plunger rising and falling with freedom in the chamber, enlarged by its t'rce comnuinication with the receiver; bllllrhen an* unusually heavy presslule"orslihck is received ivliichf'iifo/uld perhaps throw the p lllng'ewto the limit of its travel Without een thus nuzking the full proportional (lecrease of volume corresponding to the in- 1 crease of pressure, the apparatus automatiaccordance with the Well known law thatv the plrmger in chamber lO'than it the ca of such yield if there were no extensionf available vertical space can be included texture which, while allowingv the slight amountof. stretching necessary to evert' the sleeve, at the same time prevents any considerable' stretching of the fabric. No fabric or membrane hitherto known to me is entirely suitable for this purpose; but I have found that a suitable fabric can be manufactured by a combination of leather and rubber. y In making the septum here shown a' Wooden form may be used of the size of the plunger or a litt-le larger. A sheetof leather, which when made int-o sleeve form is to fit against the plunger and, when everted,,against the casing surface, is first placed loosely onthe form in single thickness with its edgesbeveled, overlapping and cemented together, so that the entire layer is of uniform thickness. A sheet ofelastic rubber is next applied, slightly stretched, completely cemented tothe leather and having 1ts edges joined in like manner.` This is convenientlyaccomplished by using rubber tubing. Another layer of leather is. then applied outside thel rubber and rmly cemented thereto. When" the.l v whole has 4been dried and removed from the form it actsmuch as though' it were an integralwhole, and the `contractive force of the "rubber causes the whole to shrink a little in diameter, introducing minute superficial wrinkles' throughout the texture of the leather, so that'without destroying its general regularity of cylindrical form it shrinks toA a" size which'its the plunger tightly, yet' upon beingl evertedv is capable of expansion so that it will fit the larger area comprising 1 the4 interior casing surface, by stretchmg theyrubber and incidentally enlarging the leather'to its original size and stretching it alittle beyond if need be. I-It is well to choose leather stock of high flexibility and expansibility. If the inherent expansibility of the leather chosen be slight the mold of i them each smoothly upon the'adjaoentfsu'pwhich the'sleeve is formed should have a larger diameter than otherwisIhe leather is contracted to fit the plunger by contraction pf the rubber, and its expansion to t the casing is preferably but little more than a .return to its original uncontracted state. Thus, the strength and normal flexibility and elasticity of the leather are retained unimpaired.

The preferred ,dimensions of parts are' such that the space between the plunger and casing is but little more than the double thickness 'of septum which occupies this space. In` operation,- the air or-other work- .ingiluidwithjn the chamber enters between the portion 'otfthe'''sleev1el-jfinsn the plunger and lits adjacent everted portion, and. separating thesetwo portions, vforces portingsurface ofthefplunger or casing, as

the case may be, leaving a minute spacerbetween them.' This prevents all friction between the adjacent surfaces of the everted septum. It also prevents the pressure n the axial direction from stretching those portions of the septum which lie against either the plunger or the casing, because such axial pressure is so slight, relative to the static friction resulting from the pressure in radial directions. The result is that the septum is not under'tension'anywhere except end that it can withstand a very high pressure. Under these circumstances the plunger slides in and out of the chamber freely, according to the balance of internal and exmost wit-hout friction, despite the very hi h pressure within, the sleeve septum mere y friction is eliminated except that incidental to guiding the plunger in its travel, and the internal friction of bending the septum at' its fold, both of which are so slight as to be tum is sustained. ultimately, 'by the cylindrical walls of the plunger, upon which it casing, upon which it acts radially outward; and bythe septum at the fold, which is theonly place theoretically having pressure tending to stretch or'rend the septum. The stress atthat point depends upon the anmay under some circumstances be almost infinitesimal, the septum is well able to sustain it `andvis not liable to rupture, even under great intensity of pressure.

In fastening one end of Ithe septum ,to the plunger and the other end to Jthemasng head the problem is to provide a connection strong and firm' enough to withstand "the This problem is solved by providing a rubber bed 1n the casinghead and 1n the -pl'unger head, and a continuous series of conthe rubber surface of'one piece bearing against the rubber surface ofthejnextlpiece.

a rubber disk 24, or else contacts direcitly with a rubber piece 27 which contacts ditherewith, the same connections being repeated in opposite order at the other endl of the rubber 32 of the septum', Leakage of air between the rubber pfl theQbed and the metal-surface of- Ehe cup in which it is held is prevented 'by-'the succession of corrugations above described, against whichthe .bed

Vand against which it is automatically highly compressedby the .fluid pressure contained at the fold, and at that place the part which 1s exposed is .so closely supported on either ternal pressures, with no leakage and ,alf

negligible. The fluid pressure upon the sepacts radially inward; and the walls of the f varyingT experience it will encounter in use.V

rectly with the rubber ring 2li: and the rubber 3Q. of the septum is in direct contact' so j rolling from one surface to the other.- All -v i atA nular or radial thickness of the film of fluid. As the latter may be very` slight, and

impervious to the fluid and mechanically i iro Y tiguous rubber pieces between the two beds,

Thus, 'a rubber bed 23 contacts directly with may be forcibly compressed'mechanically,

lao

i in the end GnpQOrmiHg tile heed of the oyl- .of :title ciinni ennuient nosnese Within cliounlen -lt will be observed. that the outer leather leyes 33. of the septimo is innesco between lminimi' ot'its termination, snol time no. ein con.. poss from Within the olnlnbeif to eitlaei' side, of this leather with "witnessing between two contiguous rubber *Weert/feces linden high compression, or possing;y between 'nfifnlabensuroce uncl u long se-V lles of snocbeseiye' corrugatious. The turn w ing of thelgleatlier. ends radially nword l linings `tliem n the direct line of compression lnexini di'ectitm censetivby the high paves- Sltlfe, Within the chamber, kthuis giving strong mechanical nippon to, the septum; while .tlienerinlierel fastening of the rubbei' 32 to .fille cylndnioul edge of the thick disk 24 '.nlelteeun impervious jointwhioli is free from mechanical slt-nain. lit is obvious that nny'nlnteiiiul olile qualities ,might be used fifnsleoe of the rubber, the word ron.

li tliez'eore nseol in tliis specification tthe claims more in e.` gener-ic` sense, meeting e ,materiel lie-ving the well gnown ettiibutes yoi rubber, than as c limitw. "on to ein specific. meteriul. The n xolierv so sneller: connection is also @DWH iii -Fg- 5, in which. oneofthe leathersv ot tlie'septnm would nntueolly come between two rubber l ces, tutti -ngthin eifel-teil whim' connec- .nis ntoflnoeclioossing wound tlie endortntll leutlienonil. goining the two rubbers, nottending lie intervening. leethei'. Anteotnie' fet-tile 'robber scrubber connect nos the eeey eeneteloilty of joints Leitende... with tllsn mind; itis pre-l geivz'etiinnito cementltlie leather 33 either to tliepiunggerlieed on totliecssing heed. The tfiiloteigs "and 2l, with ,penlinpslintervenles .poele 2l, une, however, cemented together .im .nhert distance. This lies en importent @upon the commentant utility ,ot the beeenee .it enables the septum ii its nttoehed, glislzsl, to sepexetetl i Y ..gr et eeclt @Inl` snol n new'one inserted ,its niece, Without ,dislocnting the rubber ""oefl llicnnlilier local may be more sely lield. in looetion, if desired, by proop .efneteining 'shoulder e0; enti in the 'onction ndicetietl in Figs. it end 3 the .er .elige of the cylindrical casing impliegos nnnulerly against the 'loool contained iider, serving also to intein the seid. in i p ln Fig. l' the septum. "euci-itszattechefl end disks elfo fepresenteil es coverin the cntire interior of tile chameleon, the cils s being pierced where necesseiry for pesssge ot the y central wel, et which Vpoint lisci ont is mede f V tight. by the seme methodsenilnfithequul tncility, es elsewhere; and. ,the eniul location? ofi' this rod assists in 'geiiiingtneperts enti oleo contributes to. 'solve-fthe mechanical problem of escingi-tlieimgenyoue costing lflisncoxnmnllieetion einbo with the outside. The upper hell of the septum as shown in Figs. l, 3 and 4:, and its n'iidwoy of eithere casing or o plunger is shown enlarged in Fig. ,6, in which the `cy lindrcnl Wall of the casing or plunger is parte@ mto tvqo sections screwed together :it 4l and clamping between them the septum engl. The letter may be arranged upon the yloifxnocilllie elreuily described.

les also sti leather rings 42, 43 which As sli-own, it

liolel the sept-nm end in shape to lit the seat pruvitled. in this form the iulober filling 2l' oi' Fig. ltukes the sli-ape of en. averted' connector 27', making conta/et with the rub- 'bei of the septum, `passing around the end,

olf the leather und making Contact with the y rubber lied.

.ln the moclicatio'n of the invention shown in Fig. the4 oasingis held by o ,lalternlly extending beam of the vehicle fneme, .1n`nliich the receiyei extension of the jolxoniioerj 10 oont-eined. .en alternative arrangement of the passages the-centml rod is shown. The stock ol' ln this ligure the plunger has u downward extension 51, which hos shearing at 52 against an `en` tension ott the cosing for the purpose otk gudn the plungenoccurstely in its travel.

passes, the vehicle wheel being represented ,at 55. A551013 5,6 in the casing' permits tlie vaxle bei to truvel up and down with the 'tellingen according to the elastic notion oli44 the apparatus. f llie lower extension of 'the casing may loe supported by a bracket ,57. The cnclsl of the slot 56 furnish stops .The p Unger stock' is pierced by u liole 53 1 through which the axle bei.' 54 of the vehicle i which muy iiinittlie travel of the plungery 'to prevent, excessive strain upon the sep! tum., As tlnxs eri'nngetl, the weight ol the 'vehicle nml all shocks v.received fro-1n the road by the Wheels are transmitted through Vthe treme 56, the compressed contents oit'`v `chamber ltbthe plunger, the axle bar 54,

end.y the Wheel 55. The'l locuiing between the plunger and the axle but" is tangential, one surface being curved. In case an obstaole is encountered luy the' wheels on one leide only of the vehicle, this construction permits such shook to be absorbed through ithBspI-ing on thatl side; and the incidental elevation of one end of 'the axle bur does not yi'e'cl. the vehicle, because the axle bor is lfree to roll and slide a little et its nearing with the plunger to make compensation.

Another form of the invention is shown s' in Fig. Il, in which the axial 2:06.29 pierces;

onoentl wall only of the expansible cham- Bencini hos u sliding extension 29', with 'a poet 23,6 et its extremity in position to be engaged and closed by o .rubber-piece 28 on the plunger lteetl`-illhe ,upward motion. m9

of `the plunger, which corresponds to the compression of the spring resulting from a shock encountered on t-he road, proceeds freely, but its downward motion is retarded by tie closing ot' ball check valve 37. It the upward motion proceed far enough for pad 28 to close port 36 it is retarded from Ythere onward by this partial impairment of tree communication through passage 84 with the receiver, and when the last of the ports 38', in the extension has been driven within the {ixedvportion of the tube 29 all communication with the receiver is cut otl' and the volume of the resisting chamber is limited correspondingly. Upon the downward Aor return motion, air is gradually admitted to chamber 10 from the receiver through ports 3S after the uppeiI end of extension rod 29 has uncovered port 3e when free communication is again estabn lished from the receiver to passage Sil; but until then it is restrained by check valve 37 and can flow only as permitted by the small lay-passage 38.

In assembling the sleeve in the casing the ends of the supporting leather 33 may irst be turned inwardly upon the end ot the plunger, on bed 23; the lilling strip 27 pnt in place; the rubber disk 24 placed next, and the rubber 32 of the septumjoined to its periphery; the ends of the other leather 31 turned over it, and the fillet and retaining cap put in place. After this, the

.upper leather washer 30, which is ultimately to be attached to the opposite end of the chamber, may be laid loosely 'on the retaining cap 26, the inner leather 3l olf the septum crimped over upon it, the top disk 24 placed thereon and the other end ot the rubber 32 of the septum joined to its periphery; the end of the supporting leather 33 bent radially inward thereon and the upper illing strip 27,1aid with it. Then the parts thus assembled may be inserted in the casing with rod 29 entering the recess 2S; and when the casing and plunger are/ pressed firmly together the parts inclosing the upper end of the septum, which have been lying loosely on ring 2G, will be forced into the upper end of the casing and become seated against the upper bed 23, and will be retained there by the corrugations on the axial rod 29 and also, when the apparatus is-iu operation, by the expansive forces of the fluid within the chamber. To remove the septum when thus arranged, it is only necessary to remove the packing l2 and other obstacles, so that the plunger can be pulled downward, when the fold oit the .septum will travel to its limit and, becoming bent around the fillet 25, will, upon further pullinO', separate from the upper hed 23, to which it has been attached with only a narrow cemented surface for this purpose. Upon removal from the apparatus in pla ce .of one thus removed, by an amateur, y

in case of need arising at a distance from the ordinary facilities of a shop.

The principles herein described may be applied in a variety of equivalent ways, des pending upon the needs of the partcula@ vproblem in hand, without departing from the scope of the patent. Thus, the terms ring and disk as related to the part 24 or bed 28 are equivalent, the disk being a perforated plate or not, according as an axial rod is used or not,| or it may take the form of having a very large central perforation, as indicated in Fig. 6. rEhe passages and ports 3ft, 34', and others may he' made ot" larger capacity, as the case may require, by multiplyingtheir number. ln the form shown in Fig. l the hinged brace bars 1 3 form an inexpensive and powerful support. for guiding the motion of the two parts oit the chamber in their movement relative to each other, saving the expense and risk or breakage of tempered metal, which has heretofore been used for springs, also re! quiring less metal to provide the necessary strength against torsional strains, owing to the short length of these arms. The bearings of the moving parts may be lubricated in any suitable manner. In Fig. l a quantity ot' oil is shown in the bottom of recess 28 for lubricating the rod 29; and outside stop rods are shown for preventing undueexpansion ot the chamber. Any other suitable means of guiding the parts may be employed, and in Fig. 3 an arrangement is shown which is especially useful in connection with stub axles. The axle bar 54 may be considered either as extending across to the wheel on the other side of the vehicle or as constituting merely a stub (See Fig. 7) stopping where it is herf` represented as broken ott. The stub form has many advantages in that it permits the wheel which encounters a minor obstruction on the road to rise and pass over the obstruction, its spring yielding as necessary, Without raising the weight of the body ofthe axle or vvehicle frame; and this momentary elevation of the wheel is facilitated by the extraordinarily long bearing which this invention provides for up and down sliding, one end of the. bearing being in the packing 12 and the other a conside 1able distance below at 52, the lstress being received midway where the axle pierces the stock of the plunger. Each wheel maybe mounted, as shown 'in Fig. 7, on a stub axle under a spring ot the type shown in Fie'. 3, and the vehicle body itself may be mountedl therebeing a/'fastening therefor, comprising a cup in the chamber Wall and a rubber bed therein, there being a projecting part of the chamber'wall locking said bed in place.

'10.' Thev combination, in an expansible chamber' comprlsing -a round casing and a plunger, of an everted/sleeve septum, and a plunger, Vof an everted sleeve septum, and a thick impervious disk in the .chamber wall,

. the septum being. arranged 1n impervious contact, on the perlphery thereof, a fillet retaining it in place,`and means to sustain the fillet against displacementl in vthe axial direction.

v 1 2. In apparatus of the class described, a

L septum having an external supporting layer, y:und-an end fastening therefor comprising 'rubber disks between which said layer is non-adhesively inserted; there being also adhesive rubber connection between sai disks. u

, 13. In apparatus of the class described,- a septum having an external supporting layer, and an end fastening therefor comprising rubber disks between which said layer is non-adhesively inserted radially; there'being also a rubber layer inserted between Said disks, adhesively attached to each; and the Whole arranged subject to expansive pressure of the chamber.

14. An expansible chamber, comprising a round casing, a plunger therein, soft, resilient, impervious disks covering the opposing heads of theplunger and the casing,

and an everted sleeve septum joined to each;

there being a passage piercing one head and disk, affording communication with the eX- terior of the chamber.

Signed by me at Boston, Mass., this 16th day of May, 1910.

. HENRY E..OXNARD. Witnesses:

HAROLD S. LYON,

EvERnT'r E. KENT. 

